Shares of the Seattle company at last check were off 1.1% at $3,188.
The General Court, the European Union's second-highest, ruled that Amazon had not enjoyed a selective advantage in its tax deal with Luxembourg. The court is based in Luxembourg.
"The commission did not prove to the requisite legal standard that there was an undue reduction of the tax burden of a European subsidiary of the Amazon group," the judge said, according to the National Post.
The General Court's decision can still be appealed to the EU Court of Justice, Europe's highest.
The EU in 2017 charged that Luxembourg had granted undue tax benefits to Amazon. The bloc argued that the company was allowed to pay four times less tax than other local companies subject to the same national rules.
The Amazon ruling is being seen as a setback for European Competition Commissioner Margrethe Vestager, who has gone after various aggressive tax deals, with mixed success.
The EU competition enforcer did receive court backing for its order to Fiat Chrysler Automobiles (FCAU) - Get Stellantis N.V. Report to pay back taxes up to 30 million euros ($36.3 million) to Luxembourg. The carmaker has appealed to the Court of Justice.
Amazon did not immediately respond to a request for comment.
But the company told TheStreet in an email that it welcomed the court’s decision, "which is in line with our longstanding position that we followed all applicable laws and that Amazon received no special treatment.”